The University of AkronSummit College

Business Technology DepartmentComputer Information Systems

2440: 145 Operating Systems

Introduction to UNIX/LinuxInstructor: Enoch E. Damson

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Operating System

The most important program running on a computer

It helps: Store information Process data Use application software Access all hardware attached to a computer Control all the computer’s resources Provide the basis upon which application

programs can be used or written

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Types of Operating Systems

Different computer systems can have different operating systems

For example: Operating Systems for Desktop PCs

Microsoft Windows Mac OS Linux

Operating Systems for Server Computers Microsoft Windows 2000 Server Microsoft Windows Server 2003 UNIX/Linux NetWare Mac OS X Server

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Types of Operating Systems…

Other operating systems include: Operating Systems for Mainframes

IBMS’s MVS (Multiple Virtual Storage) z/OS

Operating Systems for Network Servers Novell NetWare UNIX/Linux, Windows 2000/XP Windows Server 2000

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Types of Operating Systems…

Other operating systems include: Operating Systems for Cellphones

Google Android Symbian Palm OS (HP WebOS) RIM Blackberry OS Apple iOS (iPhone) Windows Mobile

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Operating System Components Some of the components of operating systems

include: Application Programming Interface (API) –

software designed to communicate with the application software and the user

Basic Input/Output System (BIOS) – provides the basic input/output functions to communicate with system devices, such as monitors, keyboard, disks, etc

Kernel – the core of the operating system that coordinates operating system functions, such as controlling memory and storage

Communicates with the BIOS, device drivers, and the API to perform these functions and also interface with the resource managers

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Operating System Components…

Other operating system components include: Device drivers – programs that take requests

from the API via the kernel and translate them into commands to manipulate specific hardware devices, such as disks, keyboards, monitors, printers, etc

Resource managers – programs that manage computer memory and central processor use

Optional drivers – for other functions and devices, such as sound

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Characteristics of Operating Systems

One way to look at a computer and operating systems is to consider them in terms of one or more of the following characteristics: Single-tasking Multi-tasking Time-sharing Batch processing Real-time Multiuser

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Single Tasking Systems

Executes only one process at a time Generally restricted to

microcomputers and certain specialized applications

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Multi-tasking Systems

Executes more than one program at a time for a user

It can run several programs in the background while users are working on another task in the foreground

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Time-sharing System

A central computer system that is used by multiple users and applications simultaneously Mainframe computers typically fall into

this category Most of the work is done in batches or

batch processes

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Batch Processing Systems

Execute programs (batch process) that do not require active user intervention

Normally uses a noninteractive I/O devices such as disks or document scanners for input and returns results to those same devices

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Real-time Systems

An operating system that interacts directly with the user and responds in real time (immediately or almost immediately) with required information Windows XP and Mac OS X are

examples of these systems

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Multi-user Systems

Supports multiple users who are accessing the computer’s and operating systems’ hardware and software facilities Both time-sharing and real-time

systems can be multiuser systems

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Operating Systems Platforms

The main operating system platforms include: Windows: by Microsoft Corporation Mac OS: by Apple UNIX

Linux Solaris

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The UNIX Operating System Multiuser, multitasking operating systems with built-in

network functions Can be used on systems functioning as:

Dedicated servers in a server-based network Client workstations connected to a server-based network Client/server workstations connected to a peer-to-peer

network Standalone workstations not connected to a network

UNIX/Linux are: Multiuser systems – allow many people simultaneous

access and share the resources of a server computer Portable – can be used in a variety of computing

environments

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A Brief History of UNIX/Linux

Developed in the 1970s by a group of inventive scientists at Bell Laboratories. The created an operating system consisting of: Kernel – main program to control the CPU and

all other hardware Utilities – a collection of user and system

programs Filesystem – a structure for keeping and

locating data in files on the hard drive

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UNIX Versions

There are two major versions of UNIX: AT&T UNIX version V Berkeley UNIX

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Other UNIX Systems

There are several versions of UNIX running on Sun, HP, IBM, etc that are slightly different: Linux Solaris UnixWare

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Linux

Linus Torvalds and other Internet accomplices wrote Linux (a UNIX look-alike OS) and made it available for free in its basic form

Versions of Linux include: Ubuntu OpenSolaris Fedora Red Hat OpenSuse Knoppix Debian

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Linux Shells

Versions of UNIX shells include: sh – Bourne shell (UNIX 7th Edition) bash – Bourne-again shell (GNU) tcsh – Popular extension of the C shell csh – C shell (BSD) jsh – Job control shell (SVR4) ksh – Korn shell (Bell Labs) rsh – Remote shell (TCP/IP) zsh – Popular extension of the Korn shell

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Linux GUI Desktops

Mainstream desktop environments for Unix-like operating systems using the X Window System include: KDE GNOME LXDE Xfce